A Mixed Solar Core, Solar Neutrinos and Helioseismology

We consider a wide class of solar models with mixed core. Most of these models can be excluded as the predicted sound speed profile is in sharp disagreement with helioseismic constraints. All the remaining models predict $^7$Be and/or $^7$B neutrino fluxes at least as large as those of SSMs. In conclusion, helioseismology shows that a mixed solar core cannot account for the neutrino deficit implied by the current solar neutrino experiments.Comment: 6 pages, RevTeX, plus 5 postscript figure

Bounds on neutrino magnetic moment tensor from solar neutrinos

Solar neutrinos with non-zero magnetic moments will contribute to the electron scattering rates in the Super-Kamiokande experiment. The magnetic moment scattering events in Super-K can be accommodated in the standard VO or MSW solutions by a change of the parameter space of mass square difference and mixing angle-but the shifted neutrino parameters obtained from Super-K will (for some values of neutrino magnetic moments) become incompatible with the fits from SNO, Gallium and Chlorine experiments. We compute the upper bounds on the Dirac and Majorana magnetic moments of solar neutrinos by simultaneously fitting all the observed solar neutrino rates. The bounds the magnetic moment matrix elements are of the order of 10^{-10} Bohr magnetron.Comment: 9 pages latex file with 6 figures; References added, typos corrected, matches version to appear in Phys Rev

Direct determination of the solar neutrino fluxes from solar neutrino data

We determine the solar neutrino fluxes from a global analysis of the solar and terrestrial neutrino data in the framework of three-neutrino mixing. Using a Bayesian approach we reconstruct the posterior probability distribution function for the eight normalization parameters of the solar neutrino fluxes plus the relevant masses and mixing, with and without imposing the luminosity constraint. This is done by means of a Markov Chain Monte Carlo employing the Metropolis-Hastings algorithm. We also describe how these results can be applied to test the predictions of the Standard Solar Models. Our results show that, at present, both models with low and high metallicity can describe the data with good statistical agreement.Comment: 24 pages, 1 table, 7 figures. Acknowledgments correcte

Do Solar Neutrino Experiments Imply New Physics?

None of the 1000 solar models in a full Monte Carlo simulation is consistent with the results of the chlorine or the Kamiokande experiments. Even if the solar models are forced artifically to have a \b8 neutrino flux in agreeement with the Kamiokande experiment, none of the fudged models agrees with the chlorine observations. The GALLEX and SAGE experiments, which currently have large statistical uncertainties, differ from the predictions of the standard solar model by $2 \sigma$ and $3 \sigma$, respectively.Comment: 7 pages (figures not included), Institute for Advanced Study number AST 92/51. For a hard copy with the figures, write: [email protected]

Review of Solar and Reactor Neutrinos

Over the last several years, experiments have conclusively demonstrated that neutrinos are massive and that they mix. There is now direct evidence for $\nu_e$s from the Sun transforming into other active flavors while en route to the Earth. The disappearance of reactor $\bar{\nu}_e$s, predicted under the assumption of neutrino oscillation, has also been observed. In this paper, recent results from solar and reactor neutrino experiments and their implications are reviewed. In addition, some of the future experimental endeavors in solar and reactor neutrinos are presented.Comment: Proceedings of the XXII International Symposium on Lepton and Photon Interactions at High Energy (Lepton-Photon 2005, June 30 to July 5, 2005, Uppsala, Sweden). 11 figures, 5 table

How many sigmas is the solar neutrino effect?

The minimal standard electroweak model can be tested by allowing all the solar neutrino fluxes, with undistorted energy spectra, to be free parameters in fitting the measured solar neutrino event rates, subject only to the condition that the total observed luminosity of the sun is produced by nuclear fusion. The rates of the five experiments prior to SNO (chlorine, Kamiokande, SAGE, GALLEX, Super-Kamiokande) cannot be fit by an arbitrary choice of undistorted neutrino fluxes at the level of 2.5 sigma (formally 99% C.L.). Considering just SNO and Super-Kamiokande, the discrepancy is at the 3.3 sigma level(10^{-3} C.L.). If all six experiments are fit simultaneously, the formal discrepancy increases to 4 sigma (7*10^{-5} C.L.). If the relative scaling in temperature of the nuclear reactions that produce 7Be and 8B neutrinos is taken into account, the formal discrepancy is at the 7.4 sigma level.Comment: 1 figure; related information at http://www.sns.ias.edu/~jn

Constraints on decay plus oscillation solutions of the solar neutrino problem

We examine the constraints on non-radiative decay of neutrinos from the observations of solar neutrino experiments. The standard oscillation hypothesis among three neutrinos solves the solar and atmospheric neutrino problems. Decay of a massive neutrino mixed with the electron neutrino results in the depletion of the solar neutrino flux. We introduce neutrino decay in the oscillation hypothesis and demand that decay does not spoil the successful explanation of solar and atmospheric observations. We obtain a lower bound on the ratio of the lifetime over the mass of $\nu_2$, (\tau_2/m_2) > 22.7 (\srm/\MeV) for the MSW solution of the solar neutrino problem and (\tau_2/m_2) > 27.8 (\srm/\MeV) for the VO solution (at 99% C.L.).Comment: 8 pages latex file with 4 figure

Probability of a Solution to the Solar Neutrino Problem Within the Minimal Standard Model

Tests, independent of any solar model, can be made of whether solar neutrino experiments are consistent with the minimal Standard Model (stable, massless neutrinos). If the experimental uncertainties are correctly estimated and the sun is generating energy by light-element fusion in quasi-static equilibrium, the probability of a standard-physics solution is less than 2%. Even when the luminosity constraint is abandoned, the probability is not more than 4%. The sensitivity of the conclusions to input parameters is explored.Comment: PRL, Revtex, 1 figure, 5 page

Effect of Coulomb collisions on time variations of the solar neutrino flux

We consider the possibility of time variations of the solar neutrino flux due to the radial motion of the Earth and neutrino interference effects. We calculate the time variations of the detected neutrino flux and the extent to which they are suppressed by Coulomb collisions of the neutrino emitting nuclei. To properly treat the collisions, it is necessary to simultaneously include in our analysis all other significant physical decoherence effects: the energy averaging and the averaging over the position of neutrino emission. A simple and clear physical picture of the time dependent solar neutrino problem is presented and qualitative coherence criteria are discussed. Exact results for the detected neutrino flux and its time variations are obtained for both the case of a solar neutrino line, and the case of the continuous neutrino spectrum with a Gaussian shape of the energy response function of the neutrino detector. We give accurate constraints on the vacuum mixing angle and the neutrino masses required for flux time variations to not be suppressed. Pac(s): 26.65.+t, 14.60.Pq, 96.60.JwComment: 43 pages, 8 figures, 4 appendices; changed title, MSW jump probability formula and figure

Current Status of the Solar Neutrino Problem with Super-Kamiokande

We perform an updated model-independent analysis using the latest solar neutrino data obtained by $^{37}$Cl and $^{71}$Ga radiochemical experiments, and most notably by a large water-Cherenkov detector SuperKamiokande with their 504 days of data taking. We confirm that the astrophysical solutions to the solar neutrino problem are extremely disfavored by the data and a low-temperature modification of the standard solar model is excluded by more than 5 $\sigma$. We also propose a new way of illuminating the suppression pattern of various solar neutrino flux without invoking detailed flavor conversion mechanisms. It indicates that the strong suppression of $^7$Be neutrinos is no more true when the neutrino flavor conversion is taken into account.Comment: RevTex file, 10 pages, 7 postscript figure